1. Field of the Invention
The present invention relates to a driving circuit, and more particularly to a motor driving circuit.
2. Description of Prior Art
A sickbed can provide a comfortable sleeping for a patient. Especially, the medical staffs or the caretakers can operate the sickbed to make the patient feel comfortable when the patient needs to lean against the sickbed at a certain angle. Accordingly, the motor apparatus, which is used to drive the sickbed, should be provided with a safety requirement during driving the sickbed. For example, the motor apparatus must automatically stop driving when the inclined angle of the sickbed is ultimate or provide a sufficient force to support the sickbed when the sickbed is positioned at a certain angle.
Reference is made to FIG. 1 which is a block diagram of an application embodiment of the prior art motor driving circuit. A motor driving circuit 10A drives a motor unit 20 to lengthen or shorten a pushrod unit 30, thus pushing a load unit 40. The load unit 40 can be a sickbed.
However, the existing sickbed has a major disadvantage. Namely, the self-locking force, which is produced from the motor apparatus, is insufficient to firmly sustain the sickbed, thus rocking of the sickbed would occur when the sickbed is positioned at a certain angle.